The car's female driver was heading south on Highway 21 when she apparently attempted to enter the on ramp and turned left in front of a northbound tractor trailer, said Capt. Tim Pillack.

Paramedics with Waterloo Fire Rescue took her to Covenant Medical Center where she later died, police said.

The woman's identity hasn't been released pending notification of family.

The crash was just one of several accidents in the area during a morning snowfall.

In an unrelated crash, a Chickasaw Ambulance Service rig was involved in a minor two-vehicle collision on Highway 63 north of Waterloo.

No injuries were reported, and the ambulance patient was loaded into another ambulance to continue the trip to a Waterloo hospital, according to Black Hawk County sheriff's deputies.

The crash happened around 10:15 p.m. the ambulance and a passenger car were headed south on Highway 63 just south of Bennington Road, deputies said. The ambulance ended up in the median, and the car spun around and came to a stop on the west side of the road.

Medics with Waterloo Fire Rescue were called to transport the patient.